Twin filter with backwash for dry cleaning mechanism



Jan. 14, 1969 A. M CARTY TWIN FILTER WITH BACKWASH FOR DRY CLEANING MECHANISM Filed May 8, 1967 Y Z R m flf M t A m E S 3 w r w u u N .mw m R 11% H N \n m N AR T H m MM H QR Jan. 14, 1969 L. A. M CARTY 3,421,835

TWZN FILTER WITH BACKWASH FOR DRY CLEANING MECHANlSM Filed May a, 1967 Sheet 2 of2 FIG 2,

/Z 7-714, WASH/1ND 7'P/A/SE CrcLz INVENTOR. Lff' A. Mc CART) i' fiw HTTORNEX United States Patent 3,421,835 TWIN FILTER WITH BACKWASH FOR DRY CLEANING MECHANISM Lee A. McCarty, Santa (llara, Calif., assignor to Self- Service Machines, Inc., a corporation of California Filed May 8, 1967, Ser. No. 636,940

US. Cl. 8-153 2 Claims Int. Cl. D06l ABSTRACT OF THE DISCLOSURE A dry cleaning mechanism comprising a usual wash cylinder, a sump, a fill wash and rinse valve herein referred to as a fill valve, a dump valve and a solvent pump, is connected by various pipes and automatically controlled valves to a pair of filter means, the fiow of solvent through selected ones of the pipes and valves being automatically controlled in such a manner that during each fill, wash and rinse cycle of the dry cleaning mechanism selected ones of the valves are so actuated that solvent drawn from the sump will flow in parallel, and in the normal direction for filtering, through both filter means and thence through the fill value into the Wash cylinder; during a portion of each interim between successive fill, wash and rinse cycles selected ones of the valves are so automatically actuated as to cause the solvent to flow from the pump in a normal direction through one of the filter means, herein referred to as the main filter or filter means, and thence in a reverse direction through the other filter means, the latter being herein referred to as the reserve filter or filter means, and back into the sump, thereby to backwash the reserve filter so as to Wash therefrom dirt which the reserve filter had removed from the solvent during the preceding fill, wash and rinse cycle; and during the remainder of each interim selected ones of the valves are so automatiaclly actuated as to cause the solvent drawn from the sump to flow from the pump in a normal direction for filtering through the main filter only, and thence back into the sump, thereby to remove from the solvent, by the main filter means alone, as much as possible of the filterable impurities so as to reduce to a minimum the deposit of such impurities on the reserve filter.

The present invention is an improvement on Patent No. 3,291,562, issued Dec. 13, 1966, to Doyle L. Anderson for Selective Twin Filter Mechanism and Method for Dry Cleaning Mechanism and assigned to the assignee of the present patent application.

Summary of the invention Automatic filter control means and method for a twin filter dry cleaning mechanism having a usual fill valve, a wash cylinder, a dump valve, and a sump for containing a substantial volume of dry cleaning solvent, an outlet from the sump communicating with the inlet of a usual solvent pump, the later being operated continuously during, and in the interims between, successive fill, wash and rinse cycles of the dry cleaning mechanism. In a first automatically attained condition according to the present invention the outlet of the pump communiates in parallel with the inlets of a pair of filters, the outlets of which filters communicate through the fill valve with the interior of the wash cylinder of the dry cleaning mechanism during the fill, wash and rinse cycle. In a second automatically attained condition the pump outlet communicates with the inlet of one only of the filters, herein referred to as the main filter, the outlet of the main filter communicates with the outlet of the other filter, herein referred to as the reserve filter, and the inlet of the reserve filter 3,421,835 Patented Jan. 14, 1969 communicates through a bypass line with the sump, thereby to backwash the reserve filter so as to wash therefrom filterable solids deposited thereon during the preceding fill, wash and rinse cycle. In a third automatically attained condition the outlet of the pump communicates with the inlet of the main filter only, and the outlet of said filter communicates through a bypass line with the sump, the reserve filter being shut off from the pump during the third automatically attained condition.

At the time of filing the application which resulted in the issuance of the above identified Patent No. 3,291,562, it appeared that the principal use for that invention was in coin controlled dry cleaning mechanisms, and that the large commercial type dry cleaning mechanisms were committed to the use of large, non-cartridge type filters, many of which employ diatomaceous earth as a filtering medium. In the few years since that application was filed important improvements have been made in cartridge type filters, with the result that there is a great present interest in the use of cartridge type filters in commercial dry cleaning mechanisms.

The incorporation of said Patent No. 3,291,562 in these commercial type dry cleaning mechanisms does extend the useful life of the filters and improves the solvent flow during the critical fill, wash and rinse cycle by automatically cutting in the relatively clean reserve filter during that cycle in the same way that it does in the coin controlled mechanisms. It does so, however, to a lesser degree for the following reasons: In the coin controlled mechanisms, after the fill, wash and rinse cycle is completed, and the reserve filter is out 01f, leaving only the main filter on stream, the clothes remain in the wash cylinder during the spin, dry and vapor recovery operations. This povides a relatively long interim between successive fill, wash and rinse cycles, so that, as set forth in the above identified patent, the main filter and the carbon tank or filter core have sufficient time in which to restore the solvent to a clean condition. As a result a very large proportion of the filterable solids are deposited on the main filter and a small proportion thereof are deposited on the reserve filter during the fill, wash and rinse cycle, during which cycle the relatively clean reserve filter allows a full, free flow of solvent therethrough.

In the commercial type mechanisms, however, only the fill, wash, rinse and spin operations are performed in the wash cylinder, so that the fill valve is open and the reserve filter on stream during all but the spin operation and the removal of one batch of clothes and the reloading with a new batch. The drying and vapor recovery steps with these commercial type machines are performed by other mechanisms. This reduces the length of the interims between successive fill, wash and rinse cycles, during which interims the main filter operates alone in accordance with the patent. These shorter interims freqeuntly do not provide sufiicient time to thoroughly clean the solvent, with the result that a greater amount of filterable solids are deposited on the cleaner reserve filter during the fill, wash and rinse cycle of the commercial type mechanisms when both filters are operating in parallel.

Therefore, in commercial type dry cleaning mechanisms embodying the invention of Patent No. 3,291,562, the addition of the present invention washes olf a large part of the filterable solids from the reserve filter shortly after they have been deposited thereon and while they are still easily removable. This cleaning of the reserve filter during a portion of each interim 'between successive fill, wash and rinse cycles prolongs the life of the reserve filter, in sures that the reserve filter will remain clean and usable until the main filter is completely unusable, extends to the maximum the intervals between filter changes, prolongs the overall life of the filters and ensures a high rate of solvent flow during the critical fill, wash and rinse cycle essential for best dry cleaning performance.

The invention will be apparent from the following description and the accompanying drawings wherein:

FIG. 1 is a diagrammatic view showing a dry cleaning mechanism embodying the invention, and illustrating the automatically controlled condition of the valves and the paths of solvent flow during an initial portion of the interim between successive fill, wash and rinse cycles of the dry cleaning mechanism during which the reserve filter is being backwashed.

FIG. 2 is a diagrammatic view in reduced scale of the same structure as that shown in FIG. 1 but showing the automatically controlled condition of the valves and the paths of solvent flow during a second portion of the interim between successive fill, wash and rinse cycles during which the main filter only is in use.

FIG. 3 is a diagrammatic view of the same structure but showing the automatically controlled condition of the valves and the paths of solvent flow during the fill, wash and rinse cycle.

Referring to the drawings in detail, A represents a conventional dry cleaning mechanism, the usual wash and rinse cylinder of which communicates at its upper end through a fill pipe 11 with one outlet 12 of a fill, wash and rinse valve 13. This valve 13, like several others represented diagrammatically in the drawings, in an automatieally controlled two-way valve, having a valve gate 14 pivotally mounted to swing between the solid-line and broken-line positions illustrated. A conventional solenoid 15 swings the gate 14 to one of said positions, while a usual spring, not shown, returns the gate to the other of said positions upon de-energization of the solenoid. Since such valves are well known and several valve means suitable for the purpose are available on the open market, and since the valve means per se are not a feature of the invention, the details thereof are omitted.

From the other outlet 17 or the valve 13, a bypass line 18 discharges through a usual screen mesh button basket 19 into the sump 20 of the dry cleaning mechanism A.

An overflow line 21 opens from the cylinder 10 at a desired liquid level therein and communicates with the bypass line 18. A dump line 22 also communicates the bottom of the cylinder 10 through a dump valve 13 with the bypass line 18. The outlet 13]) of the dump valve 13 is sealed.

From a low point in the sump 20 a line 24 communicates with the inlet side of a solvent pump 25, which operates continuously during the entire time the dry cleaning mechanism A is in use. The discharge side of the pump 25 communicates through a line 27 and a Y-fitting 28 with a pair of two-way valves 29 and 30. The upper openings of the valves 29 and 30 communicate through lines 31 and 32 respectively, with the inlets of a pair of cartridge type filter means 33 and 34, each of which may have a carbon core 35. When required, a pair of supplemental carbon tanks 41 and 42, each having a supply of activated carbon therein, receive filtered solvent from the filters 33 and 34, respectively. While shown as individual filters, each of the main and reserve filter means may comprise a plurality of filters arranged in selected multiples and arranged for such selected supplemental control as may be desired.

A pair of flow-control valves 37 and 38, illustrated as being manually controlled, and a pair of spring-loaded choke valves 39 and 40 are provided to balance and control the flow of solvent through the supplemental carbon tanks 41 and 42 and thence to the cylinder 10 as the main filter 33 becomes progressively clogged with filterable solids during use.

The automatically actuated valves illustrated for controlling the various fiow cycles referred to herein are controlled by a usual automatic timing or programming switch 43 of a type well known in the industry, and communicating with the control mechanisms of the various valves through conductor wire circuits which are designated by the same reference numeral as the valves which they respectively control, with the sufiix :1 added thereto. Since the provision of such timed automatic switching mechanism is well within the capabilities of a routine electrical engineer familiar with such switches, the details thereof are omitted.

The other piping and valve arrangements illustrated in the drawings will be obvious from the following description of the operation of the mechanism:

Fill, wash, rinse cycle During the filling of the wash cylinder 10 as shown in FIG. 3, the various valves shown are automatically actuated to their solid line conditions in this figure by the programming switch 43, in which condition of the valves, and with the pump 25 operating, solvent is drawn from a low point in the sump 20 and is discharged in parallel into the inlets of both filters 33 and 34 and flows through these filters in the normal direction for filtering. From the outlets of both filters 33 and 34 the solvent flows through lines 44 and 45, the spring-loaded choke valves 39 and 40, a desired portion of the solvent being diverted by the setting of the valves 37 and 33 through the carbon tanks 41 and 42, the manually adjusted ilow control valves 37 and 38 and thence through a shut-off valve 48 and the fill, wash and rinse valve 13 into the cylinder 10. During this cycle valve 46 is closed as illustrated.

In FIGS. 2 and 3 the valves 37 and 38 may be adjusted from time to time as required to proportion the flow of solvent through the filters 33 and 34 and the carbon tanks 41 and 42, or to provide more pressure on the main filter 33 as the latter becomes progressively choked with filterable solids. Obviously, however, as this latter oc curs a major portion of the solvent will have to flow through the reserve filter 34 and its associated piping during each fill, wash and rinse cycle in order to provide the volume flow necessary to properly complete said cycle within the time allotted thereto by the timing switch 43.

Backwash of reserve filter During a selected, and preferably the initial, portion of each interim between successive fill, wash and rinse cycles, and in accordance with the present invention, selected ones of the valves are actuated to their respective conditions shown in FIG. 1, in which condition solvent from the pump 25 flows into the inlet of the main filter 33, through the main filter in the normal direction for filtering and from the outlet of the main filter into the outlet of the reserve filter. It then flows in a reverse direction through the reserve filter 34 so as to backwash the latter and thus remove therefrom freshly deposited, filterable solids deposited thereon during tht preceding fill, wash and rinse cycle, which solids, suspended in the solvent, are then returned to the sump 20.

By thus automatically backwashing the reserve filter 34 during a portion of each interim between successive fill, wash and rinse cycles, the reserve filter 34 remains cleaner throughout its entire life as a reserve filter than when this step is omitted. The use of this backwashing feature also causes a larger proportion of the filterable solids to be deposited on the main filter 33 than would otherwise be the case.

Filtering by main filter only During a major portion of each interim between successive fill, wash and rinse cycles, and this is in accordance with the disclosure of Patent No. 3,291,562 referred to previously herein, selected valves are actuated by the timing switch 43 to their conditions shown in FIG. 2, in which condition the flow of solvent from the pump 25 to the reserve filter 34 is cut off by the closing of valves 30 and 46. Instead, solvent flows into the inlet of the main filter 33 through the latter in the normal direction for filtering, and from the outlet of the main filter along the paths shown in solid flow lines in FIG. 2, through the valves 48 and 13, the bypass line 18 and the button basket 19 back into the sump 20.

When the main filter 33 becomes so clogged with filterable solids as to restrict the flow of solvent therethrough below a tolerable minimum, the filter cartridge 33b thereof can be removed in a usual manner and replaced with a fresh cartridge. When this is done it is recommended that the wiring connections between the timing switch 43 and the solenoids of the valves 29 and 30 controlling the flow of solvent to the filters 33 and 34, respectively, be reversed from their condition of FIGS. 1 and 2, whereby the former main filter 33 with the newly installed cartridge therein now becomes the new reserve filter, and the former reserve filter 34, "Wtih the same cartridge therein, now becomes the new main filter. The flow path resulting from this reversal is shown in dot-dash lines in FIG. 1.

By employing such reversing circuit for the filters 33 and 34, which can be done by means of a manually actuated switch installed in a conventional manner by any ordinarily skilled electrician familiar with the circuitry of conventional dry cleaning mechanisms, it thus becomes necessary to change only one filter at a time.

While the carbon tanks 41 and 42 are included as part of the illustrative system, and while activated carbon or its equivalent is known to be required for removing dye from the solvent, a sufficient amount of carbon to satisfy the requirements of the system may be provided in the filter cartridges themselves, in which event the additional carbon tanks illustrated would not be required. In any event the separate carbon tanks are not a feature of the present invention and are not, therefore, described in detail.

While I have illustrated and described a preferred embodiment of the present invention, it will be understood, however, that various changes and modifications may be made in the details thereof without departing from the scope of the invention as set forth in the appended claims.

I claim:

1. The improvement in the method of prolonging filter life and insuring a full flow of solvent during each fill,

wash and rinse cycle of a twin filter dry cleaning mechanism having a cleaning chamber with a fill valve therefor, a solvent storage sump, and a continuously operating pump actuated solvent circulating system controlled by an automatic programming switch to have a plurality of fill, wash and rinse cycles spaced apart in time by interims; which method comprises during each fill, wash and rinse cycle automatically directing the circulating solvent from the pump through a pair of filters in parallel and in the normal direction for filtering and thence into the cleaning chamber; during a portion of each interim between successive fill, wash and rinse cycles automatically directing the circulating solvent into the inlet of the main filter through the main filter in the normal direction for filtering, through the outlet of the main filter and thence into the outlet of the reserve filter, through the reserve filter reversely to the normal direction for filtering, and back into the sump; and during the remainder of each interim automatically directing the circulating solvent from the pump through only the main filter in the normal direction for filtering and thence back into the sump.

2. The method defined in claim 1 wherein the portion of each interim during which the solvent is directed from the outlet of the main filter and thence into the outlet of the reserve filter precedes the said remainder of each interim.

References Cited UNITED STATES PATENTS 2,221,210 11/1940 Soderquist 68-18 X 3,168,469 2/1965 Abdalian et a1 2l073 X 3,253,431 5/1966 Minhinnett 68-18 X 3,291,562 12/1966 Anderson 8158 X WILLIAM I. PRICE, Primary Examiner.

US. Cl. X.R. 

